Informed consent should be obtained from patients to use products (skin substitutes) and dressings containing biological material

Informing participants in clinical trials with ex vivo human tissue-engineered products: what to tell and how to tell it?

Ex vivo tissue-engineered products are increasingly entered into clinical trials. To allow prospective participants to make a fully informed, autonomous decision on their participation, we have to adapt the informed consent process by taking the specific aspects of tissue engineering into consideration. New elements in ex vivo tissue engineering are the source and manipulation of the cells in the product, the implantation of the product and the additional risks and benefits due to the construction of the product and its activity in the body. They are the result of the delicate nature of some cell types and of the complexity of the tissue engineering process. The process of informing the participant should be designed in such a way that the participant's capacity to understand the intervention and its implications is enhanced. Crucial issues, such as the aim and procedure of the trial, the risks and benefits involved and the role of the investigator, have to be clarified. We suggest that participants' understanding of the trial can be enhanced through the use of audiovisual material, by developing a simple questionnaire to direct the information process further, and by the assistance of informed third parties to help participants in their decision-making processes.

Venous leg ulcers

INTRODUCTION

Leg ulcers usually occur secondary to venous reflux or obstruction, but 20% of people with leg ulcers have arterial disease, with or without venous disorders. Between 1.5 and 3.0/1000 people have active leg ulcers. Prevalence increases with age to about 20/1000 in people aged over 80 years.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of standard treatments, adjuvant treatments, and organisational interventions for venous leg ulcers? What are the effects of interventions to prevent recurrence of venous leg ulcers? We searched: Medline, Embase, The Cochrane Library, and other important databases up to September 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 80 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: compression bandages and stockings, cultured allogenic (single or bilayer) skin replacement, debriding agents, dressings (cellulose, collagen, film, foam, hyaluronic acid-derived, semi-occlusive alginate), hydrocolloid (occlusive) dressings in the presence of compression, intermittent pneumatic compression, intravenous prostaglandin E1, larval therapy, laser treatment (low-level), leg ulcer clinics, multilayer elastic system, multilayer elastomeric (or non-elastomeric) high-compression regimens or bandages, oral treatments (aspirin, flavonoids, pentoxifylline, rutosides, stanozolol, sulodexide, thromboxane alpha(2) antagonists, zinc), peri-ulcer injection of granulocyte-macrophage colony-stimulating factor, short-stretch bandages, single-layer non-elastic system, skin grafting, superficial vein surgery, systemic mesoglycan, therapeutic ultrasound, self-help (advice to elevate leg, advice to keep leg active, advice to modify diet, advice to stop smoking, advice to reduce weight), and topical treatments (antimicrobial agents, autologous platelet lysate, calcitonin gene-related peptide plus vasoactive intestinal polypeptide, freeze-dried keratinocyte lysate, mesoglycan, negative-pressure recombinant keratinocyte growth factor, platelet-derived growth factor).

The use of Biobrane by burn units in the United Kingdom: a national study

Biobrane is a biosynthetic wound dressing, first used by Woodruff in 1979, which has many of the ideal properties of a dressing as outlined by Pruitt and Levine [Pruitt Jr BA, Levine NS. Characteristics and uses of biologic dressings and skin substitutes. Arch Surg 1984;119(3):312-22]. It is becoming increasingly popular in the management of superficial and moderate depth partial thickness burns and a range of other conditions. When used appropriately, it has been shown to reduce pain levels, healing time, inpatient stay and nursing requirements when compared to traditional dressings. We present the results of a national study concerning the use of Biobrane in the United Kingdom, highlight variations in practice, discuss the pertinent issues, make suitable recommendations and highlight the versatility of Biobrane as a wound dressing.

Bioartificial dermal substitute: a preliminary report on its use for the management of complex combat-related soft tissue wounds

OBJECTIVE

To report our institutional experience with the use of a bioartificial dermal substitute (Integra) combined with subatmospheric pressure [vacuum-assisted closure (VAC)] dressings followed by delayed split-thickness skin grafting for management of complex combat-related soft tissue wounds secondary to blast injuries.

DESIGN

Retrospective review of patients treated December 2004 through November 2005.

SETTING

Military treatment facility.

PATIENTS/PARTICIPANTS

Integra grafting was performed 18 times in 16 wounds at our institution. Indications for Integra placement were wounds not amenable to simple split-thickness skin grafting, specifically those with substantial exposed bone and/or tendon.

INTERVENTION

Patients underwent an average of 8.5 irrigation and debridement procedures and concurrent VAC dressings prior to placement of the Integra. Following Integra grafting, all patients were managed with VAC dressings, changed every 3 to 4 days at the bedside or in clinic, with subsequent split-thickness skin grafting an average of 19 days later.

MAIN OUTCOME MEASUREMENTS

The mechanism and date of injury, size of residual soft tissue deficit, indication for Integra placement, number of irrigation and debridement procedures prior to Integra placement, days from injury to Integra placement, days from Integra placement to split-thickness skin grafting, and clinical outcome were recorded.

RESULTS

Integra placement and subsequent skin grafting was successful in achieving durable and cosmetic definitive coverage in 15 of 16 wounds with two of these patients requiring repeat Integra application. Two patients with difficult VAC dressing placement had early Integra graft failure but successfully healed following repeated Integra application and skin grafting.

CONCLUSIONS

Bioartificial dermal substitute grafting, when coupled with subatmospheric dressing management and delayed split-thickness skin grafting, is an effective technique for managing complex combat-related soft tissue wounds with exposed tendon. This can potentially lessen the need for local rotational or free flap coverage.

Tissue Engineering for Cutaneous Wounds

Skin, the largest organ in the body, protects against toxins and microorganisms in the environment and serves to prevent dehydration of all non-aquatic animals. Immune surveillance, sensory detection, and self-healing are other critical functions of the skin. Loss of skin integrity because of injury or illness may result acutely in substantial physiologic imbalance and ultimately in significant disability or even death. It is estimated that, in 1992, there were 35.2 million cases of significant skin loss (US data) that required major therapeutic intervention. Of these, approximately 7 million wounds become chronic. Regardless of the specific advanced wound care product, the ideal goal would be to regenerate tissues such that both the structural and functional properties of the wounded tissue are restored to the levels before injury. The advent of tissue-engineered skin replacements revolutionized the therapeutic potential for recalcitrant wounds and for wounds that are not amenable to primary closure. This article will introduce the reader to the field of tissue engineering, briefly review tissue-engineered skin replacement from a historical perspective and then review current state-of-the-art concepts from our vantage point.

Skin grafting for venous leg ulcers

BACKGROUND

Venous leg ulceration is a recurrent, chronic, disabling condition. It affects up to one in 100 adults at some time. Standard treatments are simple dressings and compression bandages or stockings. Sometimes, despite treatment, ulcers remain open for months or years. Sometimes skin grafts are used to stimulate healing. These may be taken, or grown into a dressing, from the patient's own uninjured skin (autografts), or applied as a sheet of bioengineered skin grown from donor cells (allograft). Preserved skin from other animals, such as pigs, has also been used (xenografts).

OBJECTIVES

To assess the effect of skin grafts for treating venous leg ulcers.

SEARCH STRATEGY

We searched the Cochrane Wounds Group Specialised Register (February 2006) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2006).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of skin grafts in the treatment of venous leg ulcers.

DATA COLLECTION AND ANALYSIS

Two reviewers independently undertook data extraction and assessment of study quality.

MAIN RESULTS

We identified 15 trials - generally of poor methodological quality - involving 768 participants. In 11 trials participants also received compression bandaging. One trial (31 participants) compared a dressing with an autograft. Three trials (74 participants) compared frozen allografts with dressings, and three trials (47 participants) compared fresh allografts with dressings. Two trials (345 participants) compared tissue-engineered skin (bilayer artificial skin) with a dressing. In two trials (71 participants) a single-layer dermal replacement was compared with standard care. Four trials compared skin grafting techniques: one trial (92 participants) compared autografts with frozen allograft, a second (51 participants) compared a pinch graft (autograft) with a porcine dermis (xenograft), the third (seven participants, 12 ulcers) compared tissue-engineered skin with a split-thickness graft, the fourth (10 participants) compared a fresh allograft with a frozen allograft. The trials comparing bilayer artificial skin with a dressing reported a significantly higher proportion of ulcers healing with artificial skin. There was not enough evidence from the other trials to determine whether other types of skin grafting increased the healing of venous ulcers.

AUTHORS' CONCLUSIONS

Bilayer artificial skin, used in conjunction with compression bandaging, increases the chance of healing a venous ulcer compared with compression and a simple dressing. Further research is needed to assess whether other forms of skin grafts increase ulcer healing.

A Critical Assessment of the Directive on Tissue Engineering of the European Union

The development of tissue engineering in Europe suffers from the absence of a coherent regulatory framework. Therefore, the European Commission has drafted a directive to regulate all tissue-engineered products in a comprehensive yet flexible framework. This article analyzes the directive from an ethical viewpoint. We argue that there are shortcomings to the proposal because of disjunctures at various regulatory levels and because responsibilities of several authorities have not been clearly established. The conscious decision to exclude ethically sensitive issues from the regulation will contribute to a continued complex regulatory environment for tissue-engineered products in Europe. We suggest that, from the start, ethical issues must be considered as an integral part of the regulation of tissue-engineered products. We propose the development of a multistage regulatory framework that makes provision for the diversity of tissue-engineered products, whereby the hybrid character and the ethical sensitivity of these products are fully taken into account. We equally suggest that the general public remain involved in regulatory issues concerning tissue-engineered products.